Monday, June 03, 2013

Today's Evolutionary Psychology Post

It began (via a tweet from Martha Bridegam) with a now-deleted nasty fat-shaming tweet by a professor of evolutionary psychology, though Jay Rosen saved the tweet.

You can follow the discussion about that on Twitter. The tweeter, Geoffrey Miller apologized for the tweet.

Miller is also tweeting an enormous bunch of interesting and weird stuff about presumed sex differences in competitiveness, how women become more musically creative when they think of long-term mating (how on earth do you measure something like that????) and how men run so much faster and throw so much better than women and so on.

There's a meeting of evo-psychologists and all this is what they do. Naturally.

But among those tweets was a link to a 2011 post at Psychology Today, the bargain basement of all psychologyish leftovers, and I read it.

It's about monogamy, and how come we are no longer polygynous (one man with several women)*. I will quote the explanation we are given, which is based on the idea that monogamous groups can grow larger than polygynous groups so they win all those violent battles for world dominance:

Why can monogamous groups grow larger? Because men want wives, and if you need a lot of men on your team, you must offer them something that they want. In monogamous groups, unlike polygynous ones, high status males cannot hoard large numbers of women for themselves. The more equal distribution of women in monogamous groups means that more men can acquire wives, and fewer men have to leave the group to search for wives elsewhere. And the larger the group, the more men there are to fight in battles and to pay taxes for the funding of wars. Socially imposed monogamy, therefore, emerged in the West as a reciprocal arrangement in which elite males allowed lower-ranking males to marry, in exchange for their military service and tax contributions.

All bolds are mine. They are used to highlight the fact that this author, Michael E. Price, has a basic theory which assumes that high status males decided on everything and that wives were sorta bought and sold to get the services of the lower-ranking males.

To see what I mean, let's write that same quote with one word changed. Woman=Beer:

Why can monogamous groups grow larger? Because men want beer,
and if you need a lot of men on your team, you must offer them something
that they want. In monogamous groups, unlike polygynous ones, high status males cannot hoardmany barrels of beer for themselves. The more equal distribution of beer in monogamous groups means that more men can acquire beer
and fewer men have to leave the group to search for beer elsewhere.
And the larger the group, the more men there are to fight in battles and
to pay taxes for the funding of wars. Socially imposed monogamy,
therefore, emerged in the West as a reciprocal arrangement in which elite males allowed lower-ranking males to drink more beer, in exchange for their military service and tax contributions.

Now, that's a possible theory, sure. But what it really hinges on is the assumption that the only people with any real power in those groups were the high status men and that the women in the group did not respond in any way to the incentives the system provided. They acted like beer barrels.

There are alternative stories about the role of polygamy in the human past. Although it is true that the institution of polygyny has existed in many societies and the institution of polyandry is known to have existed in relatively few, the really important question is the numbers of actual monogamous vs. polygynous marriages in any one society. What I mean by that is this: Even a society which is formally counted as polygynous may have had very few marriages of that type in any one time period and many more monogamous marriages.

If this is the case, it is incorrect to state that humans were predominantly polygynous in the past, as Price suggests:

To answer that, we should examine the types of small-scale societies in which nearly all of our evolution has occurred. When we do so, we find that these hunter gatherer and tribal societies have, throughout the world, historically practiced polygamy. Although most men in these societies strive for polygamy, however, only a minority can achieve it, because maintaining a large family requires an often prohibitively high degree of wealth and status. Further, because it is generally difficult to store and hoard wealth in small-scale societies, even men who do achieve polygamy can usually afford no more than two or three wives. It wasn't until the emergence of large-scale agricultural civilization, a few thousand years ago, that wealth-hoarding became possible and powerful men began accumulating large harems of hundreds or thousands of women. This pattern occurred in similar ways all over the world, as Laura Betzig describes in Despotism and Differential Reproduction. So once the ecological constraints on polygamy were lifted, high status men began accumulating many more wives than they had in small-scale societies.

Bolds are mine.

This quote is confusing to interpret. First, note that Price's evidence seems to be that polygyny was rare in the distant past. Then quite recently "powerful men began accumulating large harems of hundreds of thousands of women", and Price interprets this to mean that the ecological constraints were removed.

But if polygyny actually was rare earlier, what caused the presumed evolutionary adaptation in all men to want many wives? I guess we could pedal back to the story about sperm-is-cheap and the idea that men are more promiscuous by nature. That is not the same thing as supporting multiple wives, however, assuming that the wives had to be supported and were not actually additional labor resources.

And the ecological constraints of the presumed Environment of Evolutionary Adaptations (EEA, the hypothetical place and time in which human gender adaptations are assumed to have been fixed in evolutionary psychology) surely were part of the environment which affected those adaptations?

This matters quite a bit. The usual assumption is that evolutionary adaptations were fixed when humans lived in small nomadic hunter-gatherer groups. It is more difficult to explain how polygyny of the support-all-your-wives type Price assumes could have been profitable. Note, also, that nomadic hunter-gatherer groups in the recent past have been found to be fairly egalitarian, which makes the concept of polygyny as an evolutionary adaptation for high-status men problematic.

Whatever the case might be, Price argues that humans were predominantly polygynous on grounds which have nothing to do with the question whether the numerical majority of humans were in polygynous or monogamous marriages. Which is an odd argument, in my view.

Those large harems of hundreds of thousands of wives, by the way, were extremely rare. I'm willing to bet all my chocolate reserves on the assertion that marriages were overwhelmingly monogamous even when one Sultan or pharaoh had humongous harems.

What's the point of this post? To demonstrate the hidden parts of the theory used here, in particular the assumption that societies were utterly hierarchical in the sense of being ruled by high-status men, even though the groups in the EEA are more likely to have been fairly egalitarian. And perhaps also to note alternative explanations for the rarity of polygyny among humans. Those do exist.

For instance, decreased sexual dimorphism in humans is one offered explanation. In other animals, large size differences between males and females (with the former being larger) usually denote polygyny, small or nonexistent size differences usually denote monogamy. Some argue that human females and males have evolved to become closer in size and that this could explain the increase in monogamy. What the benefits of this might have been are discussed in the linked article.

A theory off the top of my hat concerns genetic diversity. Extremely polygynous societies might have doomed themselves to extinction because of lack of such diversity. This is most likely not such a great theory, but I'm thinking of the impact of over-breeding with one male as the sire in a few dog breeds in the US. If that male carries genetic weaknesses, they are spread widely and rapidly.

Finally, from an economic point of view (or perhaps a demographic point of view), societies with extreme polygyny are inherently unstable. What's to be done with all those spare men who can never find a mate? They could be kicked out of the group as appears to be done in the old polygynous Mormon sect, but that would only work in a system where neighboring groups weren't equally polygynous.

None of my amateur theories are intended to be regarded as real explanations. I list them, because they are not considered in the original post at all.
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*Strictly speaking, the post discusses a moderate form of polygyny where some men have many wives, some are monogamously partnered and some have no partner.

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